I don't see anything in Alfaro's history that would lead me to believe he's not going to strike out a ton. He might tone it down from last season (36.6%), but he's always going to be mid to high 20s. He really doesn't walk a lot and he just loves to swing. And I don't think his power is going to hold up very well in Miami.
Honestly, I'd be willing to bet that the Marlins had better offers on the table at last year's deadline, but were too greedy. Now they're realizing that if they don't deal him, his value will only diminish.
Alfaro led the league in passed balls also! So there is that.